1. Field of the Invention
The present invention relates generally to magnetic pole defect detection methods, and more particularly to methods for detecting magnetic pole defects in perpendicular recording heads during fabrication at the wafer level.
2. Description of the Prior Art
Magnetic heads for hard disk drives are fabricated in large quantities upon the surface of a wafer substrate. Following the wafer level fabrication process steps, the wafer is cut into a plurality of rows of magnetic heads, and further process steps are then undertaken towards the completion of the magnetic heads. To save processing time, materials, and expenses, it is desirable to test the magnetic heads during the wafer level fabrication steps. With regard to longitudinal magnetic heads, a prior art magnetic pole defect detection method has been developed in which electrical current is passed through the induction coil of the magnetic head, and corresponding magnetic flux flow through the magnetic poles is measured. Therefore, with regard to prior art longitudinal magnetic heads, a magnetic pole defect testing method exists and is utilized.
With regard to perpendicular magnetic heads, the prior art magnetic pole defect detecting method is not successful. This is because a large gap exists between the magnetic poles of a perpendicular magnetic head, such that magnetic flux does not flow through the magnetic poles when an electrical current is passed through the induction coil. As a result, magnetic pole defect testing of perpendicular magnetic heads at the wafer level cannot be readily accomplished. This results in increased fabrication time, materials and expenses where defective perpendicular magnetic heads at the wafer level must undergo further fabrication steps because the magnetic pole defects are not detectable at the wafer level. There is therefore a need for a magnetic pole defect testing method for perpendicular magnetic heads that can be utilized at the wafer level to identify defective magnetic heads.